Separating wax from oil



V. VOORHEES SEPARATING WAX FROM OIL June 14, 1932.

Filed Oct. 26. 19:51

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Patented June 14, 1932 PATENT OFFICE VANDEBVEEB 'VOOBHEEB, 0] HAMIONIIS,INDIANA, ABSIGNOB TO STANDARD OIL COM- PAJIY, OF CHICAGO, ILLINOIS, AGOBPOBATION OF INDIANA.

SEPABATING WAX IBOE OIL Application fled October 86, 183}. Serial Ilo.571,088.

This invention relates to a process for separating wax from oils and itpertains more particularl to the dewaxing of v1scous etroleum luricating oils to obtain desira 1e low pour point characteristics.

' In the manufacture of petroleum lubrieating oils it is necessary toremove substantially all of the wax in order that the o l This isusually accomplished by diluting a viscous wax-bearing oil with a lightdiluent, such as naphtha, chilling the mixture to'about --20 to 40 F. toseparate out the wax, and mechanically separating the wax from the di-'luted oil. The ease with which wax may separated from oil depends on theform m which the wax is separated out, the solubility of the wax in thediluted oil, the viscosity and s cific gravity of the diluted oil, etcunder ti: temperature and pressure conditions of the dewaxing apparatus.The 0b180t of In invention is to provide a diluent which we give oilmixtures of extremely'low viscosity and low specific gravity, which willdissolve substantially no wax and which will bring about thesolidification of wax in such a manner that it can be easily separatedfrom the diluted oil. A further object is to provide a system for usingthis diluent in "such a manner that the solidified wax will becompletely thrown out of solution in a readily filterable form.

I have discovered that the normally gaseousalkyl and alkylene ethers areremarkably efi'ective as antisolvents and diluents for the separation ofwax from oil. These substances possess a low solubility for wax andtheir presence in a dewaxing mixture results in a substantially completecrystallization of wax in a form in which it can be readily removed fromthe oil. I prefer to use dimethyl ether which is a gas liquefying underpressure to a liquid'having a low density and low viscosity. Onreduction of pressure, the

liquid boils at a low temperature, removing heat from substanceswithwhich it is in contact.

Exam has of other ethers which I may use are met yl-ethlyl ether andethylene oxide, 'quefiable gases but having higher boiling points thandimethyl ether.

One of the novel features of my invention is the simultaneousrefrigeration and antisolvent dewaxing of the oil by reducing pressureon the diluted wax-oil mixture, causing the evaporation of a portion ofthe low boiling' ether. The rate of cooling can be easily regulated bycontrolling the pressure, which will, of course, have to be lower'forthe higher boiling ethers. When using dimethyl ether, pressures somewhatabove atmospheric are suitable, while lower pressures may be used withhigher boiling ethers. I may, if desired, use mixtures of the etherswith other solvents, such as the hydrocarbons. hexane, benzene. naphtha,etc. and particularly the liquefied, gaseous hydrocarbons, propane.butane, isobutane, or mixtures of propane and butane. The invention willbe more clearly understood from the following detailed description of apreferred embodiment.

In the accompanying drawing. which forms a part of this specification, Ihave diagrammatically shown an elevational plan of my improved system.

The diluent storage tank 10 is preferably designed to withstand pressureand /or it may be insulated and provided with means for cooling thediluent which is stored therein. The diluent, for example, dimethvlether, may be mixed with a light hydrocarbon preferably of about thesame boiling point (e. g. propane). in' which case the hydrocarbon willcontribute to the refrigeration efiect obtained. and the vapors of bothhydrocarbon and other will pass of together on evapora- The liquefieddiluent is conducted from storage tank 10 through pipe 11 in amountsregulated by valve 12 into mixer 13, wherein it is mixed with theviscous wax-bearing lubrieating oil introduced by pipe 14. Thewaxbearing oil may be of any type, but in my preferred embodiment I havedescribed a treated-wax-bearing, overheat lubricafin out having aviscosity of about 650 secon Saybolt at F. Such an oil may contain from5-20% of wax.

The mixture of oil and diluent is introduced by pipe 15 into chillchamber 16 which may be a large insulated drum. Instead of introducingall of the diluent with the oil I may bypass some or all of said diluentthrough pipe 17, valve 18, heat exchanger 19 and pipe 20 into the baseof said chamber. By this expedient I am enabled to chill the diluent inthe absence of wax so that there will he no accumulations of wax in theexchanger. the chilled diluent being introduced into the body ofwax-bearing oil at the base of chili chamber 16. I prefer to mix aboutone-third of the diluent with the oil in mixer 13. till the chillchamber about one-third full, then discontinue the introduction of theoil and introduce the remaining two-thirds of the diluent through pipe17-20. Finally, I have about three to five parts of diluent to one partof waxbearing oil in the chill chamber.

By operating according to this plan the temperature of the mixture inthe chill chamber may have been reduced from about 100 F. to about 40 F.by the bypassing of diluent through exchanger 19. This temperaturereduction is preferably gradual (3 to 5 F. per minute) so that it willresult in the formation of relatively large wax crystals. I con tinuethe refrigeration by withdrawing diluent vapors through conduits 21,and. manifold 2*2. compressing them by compressor 23 and returning themthrough pipe 24. con denser 25 and pipe 26 to the diluent storage tank10. In this manner I efi'ect self refrigeration. that is. I abstractheat from the liquid by the vaporation in situ of a portion of saidliquid. The cooling from 40 F. to ifi F. may be at a more rapid rate,preferablv about 8 to 10 F. per minute. Since the diluent itself has atendency to throw wax out of solution. satisfactory pour points can beobtained at dewaxing temperatures of 0 to 10 F., the pour point beingsubstantially the same as the dewaxing temperature.

The chilled slurry from chamber 16 is withdrawn through pipe 28 andpumped by pump 27 to the base 29 of filter 30 which is preferably of thevertical type wherein filter leaves 31 are suspended from a removablecover. Filtrate is withdrawn through conduit 32. valve and pipe 34 toaccumulation tank or sump from which it may be withdrawn at desiredintervals through pipe 36, exchanger 19. pipe 37. exchanger 38 and pipe99. and introduced into boiler 40 which is heated by steam coils 41. Thewax-free oil is withdrawn from the base-of the boiler through pipe 42and the diluent vapors are withdrawn through pipe 43, exchanger 38,condenser 44 and pipe 45 to diluent storage 10. Vapors from sump 35 andfilter 30 are withdrawn through pipes 46 and 47 in amounts regulated byvalves 48 and 49: these vapors are compressed in compressor 50 andreturned through pipe 51 and condenser 52 to the storage tank 10.

When a cake has built up on the filter leaves, the liquid in the filterpress is forced back into the chill chamber and the cake is dislodgedfrom the leaves and withdrawn from the base of filter 30 through a largevalve 54. It is then forced through conduit 55 by means of screw 56driven by motor 57 into suitable apparatus for recovering diluent vaporsand separating the wax from the entrained oil.

The particular feature of my invention is the use of a wax antisolventas a refrigerant, the refrigeration being efi'ected by the directvaporization thereof. This brings about a saving in the cost ofrefrigeration which is augmented by the fact that the refrigeration needonly be carried to about 0 to 10 F. to obtain the desired pour points,while heretofore it has been necessary to refrigerate with temperaturesas low as 40 F. or even -60 F. The use of higher dewaxing temperaturesalso increases the rate of filtration and makes it possible to obtain amore complite separation of oil from wax on the filter ca e.

While I have described in detail a preferred embodiment of my inventionit is understood that I do not limit myself to the details hereinaboveset forth except as defined by the following claims:

I claim:

1. The method of separating wax from viscous oils which comprisesdiluting said oil with a liquefied normal y aseous ether, chilling thediluted oil to a dewaxing tempera.- ture whereby the wax is thrown outof solution, and mechanically separating said wax from said diluted oil.

2. The process of claim 1 wherein the refrigeration is accomplished bydirect vaporization of a portion of the diluent ether.

3. The process of claim 1 wherein a light hydrocarbon having about thesame boilm point as the diluent is admixed with said diluent.

4. The process of dewaxing a viscous mineral oil comprising dilutingsaid oil under pressure with a solvent selected from the classconsisting of the normally gaseous alkyl and alkylene ethers,redueingthe pressure on the solution, permitting a portion of thesolvent to evaporate and thereby cooling the solution to a lowtemperature at which the Wax is substantially all crystallized from thesolution, separatingthe wax from the oil and solvent, and subsequentlyrecovering the remaining solvent from the oil.

5. The process of dewaxing a mineral lubricating oil comprising dilutingthe oil under pressure with a diluent containing dimethyl ether, coolingthe diluted oil by reducing pressure and evaporating a portion ofdimethyl ether, thus causing the wax to crystallize from the dilutedoil, and subsequently separating the wax from the oil.

dcr pressure with a diluent containing ethylv ene oxide, cooling thediluted oil by reducing pressure and evaporating a portion of theethylene oxide, thus causing the wax to crystallize from the dilutedoil, and subsequently separating the wax from the oil.

In witness whereof I have aflixed my signature.

VANDERVEER VOORHEES.

DISCLAIMER 1,862,874.Vanderveer Voorhees, Hammond, Ind. SEPARATING WAXFROM OIL. Patent dated June 14, 1932. Disclaimer filed April 20, 1933,by the patentee, and the assignee, Standard Oil Company (Indiana).

Petitioners disclaim claims, 1, 2, 3, 4, and 5 of said' patent to wit:

1. The method of separating wax from viscous oils which comprisesdiluting said oil with a liquefied normally gaseous ether, chilling thediluted oil to a dewaxing temperature whereb the wax is thrown out ofsolution, and mechanically separating said wax from said uted oil. c

2. The process of claim 1 wherein the refrigeration is accomplished bydirect vaporization of a portion of the diluent ether.

"3. The process of claim 1 wherein a light hydrocarbon having about thesame boiling point as the diluent is admixed with said diluent.

4. The process of dewaxing a viscous mineral oil comprising dilutingsaid oil under pressure with a solvent selected from the classconsisting of the normally gaseous alk l and alkylene ethers, reducingthe pressure on the solution, permitting a portion 0 the solvent toevaporate and thereby cooling the solution to a low temperature at whichthe wax is substantially all crystallized from the solution, separatingthe wax from the oil and solvent, and subsequently recovering theremaining solvent from the oil.

5. The process of dewaxing a mineral lubricating oil com ising dilutingthe oil under pressure with a diluent containing dimethyl ether, coolingthe diluted oil by reducing pressure and evaporating a portion ofdimethyl ether, thus causing the wax to crystallize from the dilutedoil, and subsequently separating the wax from the iofliml Gazette May16, 1933.

dcr pressure with a diluent containing ethylv ene oxide, cooling thediluted oil by reducing pressure and evaporating a portion of theethylene oxide, thus causing the wax to crystallize from the dilutedoil, and subsequently separating the wax from the oil.

In witness whereof I have aflixed my signature.

VANDERVEER VOORHEES.

DISCLAIMER 1,862,874.Vanderveer Voorhees, Hammond, Ind. SEPARATING WAXFROM OIL. Patent dated June 14, 1932. Disclaimer filed April 20, 1933,by the patentee, and the assignee, Standard Oil Company (Indiana).

Petitioners disclaim claims, 1, 2, 3, 4, and 5 of said' patent to wit:

1. The method of separating wax from viscous oils which comprisesdiluting said oil with a liquefied normally gaseous ether, chilling thediluted oil to a dewaxing temperature whereb the wax is thrown out ofsolution, and mechanically separating said wax from said uted oil. c

2. The process of claim 1 wherein the refrigeration is accomplished bydirect vaporization of a portion of the diluent ether.

"3. The process of claim 1 wherein a light hydrocarbon having about thesame boiling point as the diluent is admixed with said diluent.

4. The process of dewaxing a viscous mineral oil comprising dilutingsaid oil under pressure with a solvent selected from the classconsisting of the normally gaseous alk l and alkylene ethers, reducingthe pressure on the solution, permitting a portion 0 the solvent toevaporate and thereby cooling the solution to a low temperature at whichthe wax is substantially all crystallized from the solution, separatingthe wax from the oil and solvent, and subsequently recovering theremaining solvent from the oil.

5. The process of dewaxing a mineral lubricating oil com ising dilutingthe oil under pressure with a diluent containing dimethyl ether, coolingthe diluted oil by reducing pressure and evaporating a portion ofdimethyl ether, thus causing the wax to crystallize from the dilutedoil, and subsequently separating the wax from the iofliml Gazette May16, 1933.

